The present application claims priority to European Patent Application No. 00 121 032.7 filed Sep. 27, 2000, the disclosure of which is hereby incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a method for checking the filling or the content of compartments or pockets in a blister package in particular for pharmaceutical products.
2. Scope of the Prior Art
Powdery or solid pharmaceutical substances are packaged in pockets in blister packages and are obtained by the patient in such packages. Liquid and pasteous substances can also be packaged in pockets of blister packages. All such substances may comprise one compound or several compounds.
With pharmaceuticals, the highly precise filling per pocket of the desired quantity is crucial, something that has led to the creation of very elaborate control devices. Conventionally, the quantities are checked by weighing them.
A device for weighing pharmaceutical receptacles, particularly ampoules, is known from DE 199 20 494 A1 which shows a weighing device with weighing pockets for weighing the receptacles prior to and after they are filled. By means of a gripper the receptacles are removed during a resting phase of a rhythmically operating conveyor device in the vicinity of the filling facility and are weighed. Then, the receptacles are re-fed to the conveyor device for filling and after being filled are again removed and weighed. Even if the device is supposed to be relatively simple in structure, as indicated in this publication, and only requires very little space, still its main disadvantage lies in the fact that due to weighing the receptacles, e.g. the pockets, twice prior to and after they are filled, a considerable amount of time is needed for checking the filling.
Up to 120 pockets per second are filled on a high-performance blister machine developed for filling of solid and powdery pharmaceuticals. Due to this high quantity, control is carried out by weighing them on a random basis. In doing so, a sample is automatically drawn, that sample is fed to the scale by means of a handling system, the filled pocket is weighed, the pocket emptied, for instance by blowing out the powder, the empty pocket is weighed and the differential value is accordingly calculated.
The random sampling check is, however, not sufficient for ensuring correct filling of the pockets since with filling quantities below one milligram per pocket it is obvious that deviations of the most minute filling quantities mean incorrect filling.
The object of the present invention is to provide a method for checking the filling or content of pockets in a blister package in particular for pharmaceuticals, where the pockets were filled with a substance, with which process a very large number of the filled volumes can be checked and the checking occurs fast enough to enable the control of a filling which is performed with high-performance machinery.
The method according to the invention is provided for checking the filling or content of pockets of a blister package in particular for pharmaceuticals which is filled with a powdery, solid, liquid or pasteous substance. The volume of the substance is detected by a sensor and the detected volume value is supplied to an evaluation device in which a comparison of the detected volume value with a volume target value is carried out.
This ensures that the volume filled in the packages is detected and checked while avoiding an interruption of the filling process by a weighing process and avoiding a loss of the volume of pharmaceuticals in the random sampling process.
With direct detection of the filled volume, the time thus needed is extremely reduced when compared with the time needed for weighing as described above, allowing for a significant Increase in the filling quantity per unit of time.
In particular, detection of the filled volume occurs without any contact, which likewise contributes to a further saving of time in checking.
Preferably, the comparative value between the volume value detected and the volume target value is displayed by means of a display device. In this way, for instance, filling machine operating personnel can at any time check on the filled volume.
If, according to the invention, each pocket of the package is detected by means of a sensor, then there is a 100-percent check on the filled pharmaceuticals, which ensures the correct filling of all pharmaceuticals.
Preferably, the number of sensors provided should correspond to the number of pockets in a package row, in which way a so-called line sensor is created with which all pockets in a package row can be checked. Recording can thus take place both if the package is in motion as well as if it is at rest.
Alternatively, the number of sensors can correspond to the number of pockets of a package, i.e. filling is checked with a so-called matrix sensor. It is obvious that with simultaneous checking of several or many pockets a correspondingly rapid filling can be achieved.
For highly precise recording of the volume of the substance located in a pocket, detection is accomplished by means of a matrix sensor when the package is at rest. This resting phase is, however, extremely brief since the sensor is in a position to carry out recording in an extremely short period of time. As an example: for recording, only several microseconds are required.
It is particularly advantageous if the sensor used in the process is a capacitive test probe having a simple structure and providing a detection signal which can be processed in a simple manner and which preferably measures the induced dipol moment (the electrical polarization) in any given volume of any material by means of a high frequency alternating field.
Alternatively, the sensor can also be an optically three-dimensional image recording sensor with the aid of which the filling volume can be calculated exactly.
The substances to be checked can be powdery, solid, liquid or pasteous substances, in particular pharmaceuticals. Such substances may have one compound or several compounds.
Further details, features and advantages of the present invention emerge from the following description with reference made to the drawings.